Micromachined vibratory gyroscopes are increasingly used in applications that require large dynamic range and large bandwidth such as gaming controllers and smart user interfaces. The popularity of such gyroscopes has grown, in large part, due to their low cost, small size, robustness and low power consumption, attributes which had been hardly achievable with conventional gyroscopes. One such gyroscopic device is disclosed in U.S. Pat. No. 7,543,496, entitled “Bulk Acoustical Wave Gyroscope,” the subject matter which is incorporated herein by this reference for all purposes.
It is well-known that wide-bandwidth gyroscopes can transfer Coriolis signal to the sense mode faster than narrow bandwidth devices, ensuring a faster response time. However, in mode-matched gyroscopes the increased bandwidth is usually limited by the operating frequency, which is inversely proportional to the dimension of the vibrating mass, and hence the capacitive sense area. Vibratory micro-gyroscopes operating at mode-matched condition use two resonance modes of a structure with almost identical frequencies to amplify the Coriolis force induced vibration by the mechanical quality factor of the sense mode. However, because of imperfections in the fabrication process, the native drive and sense resonance modes of these devices may exhibit a frequency separation. DC voltage potentials are thus applied in a calibration step to adjust the electrical stiffness of the drive and sense resonance modes and to make their pass-bands overlap. Accordingly, a need exists for a gyroscope with an increased resonator bandwidth that is larger than the worst-case frequency separation caused by errors introduced during the fabrication of the devices.
Additionally, the bandwidth of a gyroscope restricts the response time and the operational range of the system. In order to achieve wider bandwidth, previous solid disk configurations employed high-frequency designs obtained from smaller device dimensions. However, decreased device dimension results in reduced capacitive area and sensitivity. Accordingly, a need exists for a gyroscope with increased bandwidth and dynamic range without relying on a reduction in component dimension to achieve such results.